1. Field of the Invention
This invention pertains to the field of manually-operated computer input devices, and, in particular, to manually operated film scanner input devices.
2. Background Art
Manual image scanners are well known devices for inputting textual and pictorial information to a computer. U.S. Pat. No. 4,581,761 describes a typical ergonomically-designed housing including a linear sensor that is manually dragged by the hand of a human operator (hereinafter referred to as the "user") across the text or pictorial copy. A pressure sensitive switch on the bottom of the scanner turns the unit on when the user forces the scanner against the copy, and turns the unit off when the depression force is removed. Additional functions, such as variation of the enlargement or reduction ratio, may be engaged by keys on the top surface of the scanner. Notwithstanding such functionality, the scanner operates in but one scanning mode, that is, it inputs scanned data when the bottom switch is depressed and the linear sensor is swept across the copy. (U.S. Pat. No. 4,901,364 shows another example of a scanner capable of multi-functional operation, but only one scan capability.) If playback of the scan is needed, e.g., to evaluate the pictorial information, either the computer has to collect the linear scan data for a complete raster, or, as shown in U.S. Pat. No. 3,993,865, an intermediate store is provided for first collecting data from the manual scanner at a variable rate dependent on hand motion and then repetitively reading out the data at a constant rate for television viewing.
It is sometimes desirable to formulate a preliminary scan of the copy material before the final scan is obtained. For instance, in U.S. Pat. No. 4,516,265, two scanners are employed: a first scanner does a coarse prescan to determine the positional relationship of pattern blocks on the copy (e.g., a postal envelope), and a second scanner does a fine scan on a selected block. In U.S. Pat. No. 3,873,974, the same scanner is used twice, first to perform a rapid initial scan to locate a particular pattern (e.g., white blood cells) and then to perform a rescan to examine a detected pattern in greater detail. Obviously, such dual scanning requires a positionally controlled system if the first scan is to identify parameters that would be useful in the second scan. In the '974 patent, for example, the scanner is part of a microscope stage and not subject to hand-induced variations. In a system capable of some image composition, such as enlargement or reduction as provided in the hand-held scanner described in the aforementioned '761 patent, it would be helpful to visualize what the final scan would look like before it is done. Unfortunately, such hand-operated scanners, where the motion of the hand provides the page scan, do not lend themselves to real-time previewing for composition purposes.
Apart from the realm of hand-manipulated scanners, relatively larger desk-top scanners are available for high resolution scanning of slides or negatives in color or black-and white. An example is the 35 mm Rapid Film Scanner manufactured and sold by Eastman Kodak Company, Rochester, N.Y. This scanner performs a color sequential high resolution area scan (1312.times.1024 pixel area) of color images in 18 seconds for input to a Macintosh.RTM. computer. Besides performing optical zooming, panning, and cropping, the Rapid Film Scanner has a prescan mode in which the image can be viewed either in monochrome or in color. The user selects the mode via a pull-down menu on the computer. Composing the image in color is difficult, however, because of the slow screen update rate due to the need to sequentially capture three color separations by rotating a filter wheel, and due to the color fringes which appear if the film image is moved while the separations are scanned. As a result, image composition is normally done in the monochrome mode. To then capture the image in color, the user must redirect attention to the computer, pull down the computer menu, and select the color mode. Once the color image is captured, the user must pull down the menu again, in order to return to the monochrome mode, and compose the next image. This means that the user must continuously switch from handling the scanner to handling the computer pointer, typically by manipulating a mouse. This is a tolerable situation for user scanning of only a few images, as is typically the case in applications where such a scanner is used. It is less acceptable in the case where real-time interactive image input is desired.
User-friendly zoom and crop features are compromised if the user must continually divert attention back and forth between the scanner and the computer pointer or keyboard for every image to be scanned. There is a need, consequently, for a manually operated film scanner allowing a fully-operational tactile engagement of the scanner (that is, operation of the scanner in all its modes) while providing a virtually simultaneous display of the image on the computer to which the scanner is connected.